A gas turbine engine is used to power various types of vehicles and systems. A particular type of gas turbine engine that may be used to power aircraft is a turbofan gas turbine engine. A turbofan gas turbine engine typically includes five major sections: a fan section, a compressor section, a combustor section, a turbine section and an exhaust section. The fan section is positioned at the inlet section of the engine and includes a fan that induces air from the surrounding environment into the engine and accelerates a fraction of this air toward the compressor section. The compressor section raises the pressure of the air it receives from the fan section and directs a majority of the high pressure air into the combustor section. In the combustor section, the high pressure air is mixed with fuel and combusted. The high-temperature combusted air is then directed into the turbine section where it expands through and rotates each turbine to drive various components within the engine or aircraft. The air is then exhausted through a propulsion nozzle disposed in the exhaust section.
An aircraft turbofan gas turbine engine, such as the one described above, may be exposed to numerous and varied environmental conditions. For example, the engine may be exposed to various environmental conditions that may result in ice accretion at various locations on or within the engine. Not surprisingly, such accretion can adversely affect engine performance and/or have various other deleterious effects on engine components. Thus, many aircraft include anti-ice systems to prevent ice accretion on various locations on or within the engine.
Some governmental agencies, such as the Federal Aviation Administration (FAA), require many aircraft anti-ice systems be designed to prevent ice accretion, and more specifically supercooled droplet icing, on or within the engine up to a predefined certification altitudes and temperatures (e.g., 30,000 feet, −40 degrees Centigrade). Unfortunately, it has been discovered that these anti-ice systems are ineffective, and may even contribute to ice accretion through the addition of water droplets from melting ice crystals, at least during certain atmospheric conditions, at preventing ice crystal accretion at altitudes and temperatures above the predefined certification altitudes and temperatures.
Hence, there is a need for an aircraft anti-ice system that will prevent ice crystal accretion on various locations one or within an engine even at altitudes and temperatures above the predefined certification altitudes and temperatures. The present invention addresses at least this need.